Generic drive mechanisms are specially used for driving mobile vehicles such as working machines like wheel loaders. At low speed wheel loaders require high tractions and preferably a terminal speed of 40 km/h. In a first driving range, the working range, gear shifts are an obstacle since those gear shifts are time consuming and thus prolong the load cycle.
DE 39 07 633 C2 discloses a continuously variable hydrostatic drive system in which one output shaft is driven by a first hydromotor via a first transmission part and a second hydromotor via a second transmission part, likewise, drives the output shaft. In a first driving range, both transmission parts are connected with the output shaft so that the torque of both hydromotors acts upon the output shaft. By changing the displacement of one hydromotor, the output rotational speed can be additionally changed for changing the displacement of the pump. But this is possible only up to a maximum rotational speed of the hydromotors. For this reason, there is the reduction gear part of the second motor between a mechanical separating device which, upon reaching the maximum rotational speed of the hydromotor, separates it from the output shaft so that the other hydromotor can further be accelerated up to its maximum rotational speed. Before the separating device can be opened, the motor has to be adjusted to a displacement of nearly zero. But the coupling and uncoupling of the motor produces a shift jerk.
The problem on which this invention is based is to provide a drive mechanism for a mobile vehicle where, in a first driving range, the torque of two hydromotors acts upon the output shaft and where, in another driving range, the torque of only one hydromotor acts upon the output shaft whereby the shift jerk is to be minimized and the transmission simply constructed.
The problem is solved with a drive mechanism for mobile vehicles.